Fire extinguishing system nozzle

ABSTRACT

The discharge outlet plug of a fire extinguishant nozzle is retained by an external lever system that is conditioned by the operation of a heat fusible means in response to the presence of a first temperature rise to permit release of the plug under fluid pressure in the nozzle. Holding mechanism preferably associated with the lever system is provided to prevent release of the plug unless the nozzle fluid pressure exceeds a predetermined pressure floor, and a temperature responsive override arrangement associated with the lever system is provided to disable the holding mechanism in the presence of a materially higher temperature rise to permit the plug to be expelled by fluid pressures below the pressure floor.

United States Patent [191 Woodward et al.

FIRE EXTINGUISHING SYSTEM NOZZLE Inventors: Richard V. Woodward; Richard A.

McMahon, both of Pittsburgh, Pa.

Assignee: Factory Mutual Research Corporation, 'Norwood, Mass.

Filed: Jan. 19, 1973 Appl. No.: 324,981

US. Cl. 169/40, 169/42 Int. Cl. A62c 37/12 Field of Search 169/20, 21, 37-42 References Cited UNITED STATES PATENTS Aug. 13, 1974 Primary ExaminerLloyd L. King Assistant Examiner-Andres Kashnikow Attorney, Agent, or FirmLane, Aitken, Dunner & Ziems [57 ABSTRACT The discharge outlet plug of a fire extinguishant nozzle is retained by an external lever system that is conditioned by the operation of a heat fusible means in response to the presence of a first temperature rise to permit release of the plug under fluid pressure in the nozzle. Holding mechanism preferably associated with the lever system is provided to prevent release of the plug unless the nozzle fluid pressure exceeds a predetermined pressure floor, and a temperature responsive override arrangement associated with the lever system is provided to disable the holding mechanism in the presenceof a materially higher temperature rise to permit the plug to be expelled by fluid pressures below the pressure floor.

17 Claims, 13 Drawing Figures FIG. I

PAIENIEDw 3.828.855

' sum 1 BF 3 FIRE EXTINGUISHING SYSTEM NOZ ZLE extinguishing This invention relates to spray nozzles for fire extinguishing systems of the type used in buildings for automatically discharging water or like liquid to an area where the ambient temperature rises above a predetermined value, as in the case of a fire in that area, and is primarily directed to nozzles that are effective to discharge only when the internal or input fluid pressure is above a predetermined value which is sometimes identified as the pressure floor.

Fire extinguishing systems of this pressure floor type wherein even after a fusible control or like device has nozzle outlet and is subject to internal fluid pressure includes heat responsive means that inresponse to the presence of a predetermined temperature conditions the lever system to permit the plug to be expelled or rangement that maintains the lever system in plug rebeen actuated to release condition by increased temexpelled from the outlet when the fluid pressure within a the nozzle is below a predetermined pressure floor.

Another object of the invention is to provide a novel lever system for retaining the outlet blocking plug of a fluid dispensing nozzle wherein the lever system in cludes at least two coacting levers held in operative assembly with the plug by a releasable positive holding device such as a shear pin, tension element, spring clip or the like connected either between the levers or between one of the levers and the nozzle body and adapted to break or otherwise release when subjected to force corresponding to a predetermined fluid pressure in the nozzle.

A further object of the invention is to provide a novel dual control system for a fluid dispensing nozzle wherein a lever system mounted externally of the nozzle body and operatively engaging the bottom of a plug that normally blocks the nozzle discharge outlet and is subject to internal fluid pressure includes heat responsive means that in response to the presence of a predetermined temperature conditions the lever system to permit the plug to be expelled or moved to open the outlet by fluid pressure which exceeds a positive holding force provided by means incorporated in the lever system.

A further object of the invention is to provide a novel control system of this type wherein a multiple lever system mounted externally of the nozzle body and operatively engaging the bottom of a plug that normally blocks the nozzle outlet and is subject to internal fluid pressure includes heat responsive means that in re sponse to the presence of a predetermined temperature conditions the lever system to permit the plug to be expelled or moved to open the outlet by fluid pressure, and wherein a releasable holding device such as a tension element, spring clip or the like connected between levers or between the levers and the nozzle body maintains the lever systemin plug retaining position in the absence of a predetermined fluid pressure within the nozzle.

A further object of the invention is to provide a novel dual control system of this type wherein a lever system mounted externally of the nozzle body and operatively engaging the bottom of a plug that normally blocks the fluid pressure in said nozzle. Further to this object the shear pin or the like may be a second overriding heat responsive device that operates to release said lever system to permit the plug to be expelled in the presence of a temperature materially higher than that which actuates the first temperature responsive device, regardless of the fluid pressure in said nozzle.

A further object of the invention is to provide a novel control system of this type wherein a lever system mounted externally of the nozzle body and operatively engaging the bottom of a plug that normally blocks the nozzle outlet and is subject to internal fluid pressure includes heat responsive means that in response to the presence of a predetermined temperature conditions the lever system to permit the plug to be expelled or moved to open the outlet by fluid pressure which ex-.

ceeds a predetermined pressure floor, and wherein the lever system includes further overriding temperature BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a side elevation partly broken away and in section showing an embodiment of the nozzle assembly incorporating the invention;

FIG. 2 is a section substantially on line 2--2 in FIG.

FIG. 3 is a side elevation partly in section showing a further embodiment wherein the pressure floor release is incorporated in the retainer lever system;

FIG. 4 is a side elevation mainly in section showing a further embodiment wherein the pressure floor release is a wire connection in the lever system;

FIG. 4A is a fragmentary section showing details of the pressure floor release structure of FIG. 4;

FIG. 5 is a bottom plan view of the nozzle assembly of FIG. 4;

FIG. 6 is a side elevation mainly in section showing a further embodiment wherein the pressure floor release is a spring clip between levers in the lever system;

FIG. 11 is a fragmentary side elevation mainly in section taken substantially at right angles to FIG. 10 and showing the override beam in detail; and

FIG. 1 2 is a fragmentary side elevation mainly secvlion showing another form of override beam;

PREFERRED EMBODIMENTS Referring toFIGS. l. and 2, the spray nozzle 11 comprises a tubular body 12 having an inlet designated at .13 threadedly connected to a supply pipe 14 that contains water under mains or pump pressure. A vaned internal swirl assembly 13a isfixedin the inlet. The nozzle outlet designated at 1 is normally blocked by a plug member 16 having an external groove l7'containing a compressedresilient O'-fring 18 that seals against outlet passageof 'water under normal pressures. Plug member l6hasa-slidable sealing fit in the'outlet'. A rigid projection 19 on the bottom of plug' '16 engageslever 21 of an external lever system22 that includes a further lever 23-parallelto lever 21 and a heat fusible connection '24. Lever 21 has one hooked end 25 rockably disposed in an annular nozzle body groove 26, and its other end isfulcrumedat 27 upon lever 23. The

end of lever 23 adjacent the fulcrum is hooked at'28 to be rockably disposed in groove 26, and' the other end of lever 23- is connectedby fusible connection 24 to an external body lug 29.;Fusible connection 24 comprises metal elements 31 and 32 connected respectively to the nozzle body and the lever system,'and interconnected by a solder layer 33 adapted to melt and release at a predetermined temperature.

In this embodiment the pressure floor holding action is accomplished by a mechanical interlock between a fixed post 34 upstanding from the plug member 16 and an integral socket indicated at-35' provided in the plas tic hub 13b of the swirl'asse'mbly. Socket 35 has a downwardly open recess- 4l formed'with; a restricted mouth 42 adapted to be forcibly expanded. by the conical tip 43 of postv 34which recloses aboutthe reduced section '44of the post. Normally the downwardly facing post, shoulder45 engages the upwardly facing socketshoulder 46 to resist downward displacement of I plug member 16 under-fluid pressure. M

In operation plug member l6 normally blocks the nozzle outlet, andthe fluid pressure force within the nozzle tending to expe'l the plug. is resisted by the external lever systemand the mechanical interlockat-the socket. Should a tire occur,,the fusible link 24 willseparate toreleas'e and thus condition: theexternal lever system to'permit the plug member to be expelled by fluid pressure. :If the fluid pressure within the nozzle is sufficiently high the plug post will be-pulled forcibly through the socket mouth 42 andthe plug 16 expelled.

Referring to FIG. 3, which has the same nozzle body construction and much of. the lever system arrangement as shown in FIGS; 1 and 2, the corresponding parts being similarly numbered. Therelease or mechanical interlock providingv against the plug being expelled when; the fluid-l pre'ssure inside the nozzle is below a predetermined amount is incorporated in the lever system externally of the nozzlebody. A shear pin 4 t 16 to be expelled if the fluid pressure acting on it is high enough to act'through the lever system to shear pin 47.

Once pin 47'shears, the lever system drops away and plug 16 is expelled to permit'full' discharge of extinguishant.

' In a modification of the FIG. 3 arrangment the pin 47 is not only a shear pin but is a fusible element that will melt to release elements 31 and 32 at atemperature that is'a predetermined amount higher than the fusing temperature of solder layer 33.

The operation is basically the same as for v FIG; 3 above described, but with the added feature that should the fire temperature exceed acertain maximum value the pin 47 will fuse and the plug'l6 will be expelled regardless of the fluid pressure in'the nozzle. This is a safety feature, which is desirable in that it will override the shear action should the pin 47- for example prove to be unexpectedly or accidentally resistantto the normal pressure floor force,or incase the fluid pressure is not sufficient'to expel the plugs 'but'fluid is nevertheless required. a I

FIGS. 4 and 5.illustr'ate another embodiment wherein :the pressure floor release is incorporated in the external lever system that holds the plug in the nozzle outlet. The nozzle body is essentially the same as in the previous embodiments, with .correspondingnumerals indiv prises a metal wire 67 cating corresponding parts.

A plug member 48 is slidably mounted in outlet 15 and comprises a cup-shaped element having a cylindrical wall 49 in slidingcontact with the outlet wall. Wall 49 is formed at its upper end with an external upwardly open recess -51 defining aradial open top space be tween the plug and outlet wherein is disposed a-radially compressed resilient1O-ring 52. a I

The external lever system comprises a first lever 53 intermediately engaging the'bottom of plug-48 and having one end hooked at 54 to rockablymount it inan external annual nozzle bodygroove 55. The other end'of lever 53 ispivoted on a fulcrum 56 on a second parallel lever 57 having a hooked end 58 rockably mounted in groove 55. Fulc'rum56 is the rounded end of an adjustable screw 59. The other end of lever 57 has a lug6l connected to a lug 62 on lever 53 by'a-heatfusible link 63. Link 63 comprises metal elements 64'and 65 coupled by a heat fusible solder layer 66. I

The pressure floor release in this embodiment comthat couples'levers 53 and 57 together. Referring to FIGS. 4 and 4A, wire 67 passes through an opening 68 in lever 53 and its opposite ends are imbedded tightlyin a solid body of solder 69 containedin a cylindrical shell 70 engaging the lower end allow fluid pressure in 'the'nozzle to expel the plug 48.

Should this fluid pressure exceed the pressure floor value, the resultant force exerted on the lever system will snap wire 67. The solder body 69 is fusible at a temperature that is a predeterminedamount higher than the temperature whichwill fuse solder layer 66, and should that higher temperature be attained the solder at 69 will fuseand the lever system will drop away to permit the plug 48 to be expelled regardless of the fluid pressure in the nozzle. An important feature is the disposition of the radially compressed O-ring seal in the upwardly open recess around the plugjThis has been "found to minimize any restraining action the seal ring might have on the plug being expelled as the seal ring moves with a rolling action along the outlet surface.

FIGS. 6-8 illustrate a further embodiment which is similar to FIGS. 4 and 5 and wherein the pressure floor release comprises a spring clip device 71. As shown in FIG. 8 the spring clip device comprises two L-shaped sheet metal elements 72 and 73 having their overlapping lower legs 74 and 75 underlying lever 57 and connected by a fusible solder layer 76. Solder layer 76 fuses at a temperature which is a predetermined amount higher than the fusion temperature of link 63. At least one of the clip arms is a spring leaf 77 extending over the upper lever 53 to provide the mechanical pressure floor interlock.

Should the link 63 be fused by a fire the lever system will be conditioned to permit fluid pressure inthe nozzle to expel plug 48. Should that fluidpiessure be equal to or above the pressure floor, the levers 53 and 57 will be forced apart and released by the spring clip and the plug will be expelled from the outlet.

. Should the temperature rise sufficiently to fuse layer plug 82 to be expelled by fluid pressure. If the internal fluid pressure in the nozzle exceeds the pressure floor 'the downwardly directed force acting through the plug and lever 86 will rupture strap 103 to break beam 96 and permit the lever system to fall away from the outlet.

Should the pressure in the nozzle be below the pres- I sure floor, beam 96 will hold the lever system in place.

76, the clip 71 will separate to release the lever system and permit the plug to be expelled regardless of the fluid pressure in the nozzle.

FIG. 9 shows an optional form of spring clip 78 wherein the overlapping legs 74 and 75 are rigidly connected by a rivet 79 and there is no solder layer between them. However, the spring arm 81in this form which holds the levers 53 and 57 together in the absence of a pressure floor within the nozzle is a bimetallic strip that when exposed to a temperature a predetermined amount higher than that which fuses link 63 will snap to the dotted line release position in FIG. 9 and the lever system will drop away to permit plug 48 to be expelled.

Referring to FIGS. 10-12, a plug 82 is slidably disposed in blocking position in the outlet 15. Around its upper periphery plug 82 is provided with an upwardly open recess 83 defining an upwardly open annular space containing the radially compressed resilient O- ring seal 84.

Plug 82 is retained in the nozzle outlet by an external lever system 85 comprising a first lever 86 intermediately engaging the bottom of plug 82 and having a hooked end 87 rockably mounting it on an annular flange 88 around the lower end of the nozzle body 12. The other end of lever 86 is fulcrumed as by an adjustable set screw and ball arrangement 89 upon a second parallel lever 91 that has one hooked end 92 rockably mounted on body flange 88. The other end of lever 91 has a lug 93 connected by a heat fusible link 94 to a lug 95 on lever 86. This link may be of the structure disclosed in the earlier embodiments.

The lever system also comprises an override beam unit 96 which as shown in FIG. 11 comprises opposite sections 97 and 98 having hooked outer ends 99 and 101, respectively, rockably mounted on body flange 88. Beam unit 96 is disposed at right angles to levers 86 and 91 andthe inner ends of beam sections 97 and 98 are spaced to provide an upwardly open recess 102 within which is snugly disposed lever 86'. A thin metal strap 103 extends across the bottom of recess 102 to fixedly interconnect beam sections 97 and 98, and pref- 1 erably strap 103 is secured at opposite ends to the re- However, should the fire attain the higher temperature that fuses solder layer 104, the strap 103 will separate from the lever system and allow it to drop away and the plug to be expelled regardless of the fluid pressure in the nozzle.

In order to ensure that the strap 103 will break at the proper time, beam sections 97 and 98 are formed with relatively thin cross section bending corners 105 and 106 respectively. As the fluid pressure force F,, acts downwardly on plug 82 it urges lever 86 against beam section extensions 107 and 108 at the bottom of recess 102, so that the flexible lever sections are oppositely rocked about their bending corners. This places strap 103 in tension, and the cross section of strap 103 is so designed that it will break when subjected to tension force corresponding to the pressure floor.

FIG. 12 shows an embodiment similar to FIG. 11 but wherein the override beam 109 comprises opposed beam sections 111 and 112 having their inner ends spaced at an effective recess 113 to snugly receive lever 86, and across the lower end of space 113 extends the thin metal strap 114 secured at opposite ends by solder layers 115 to the beam sections. The outer ends of the beam sections in this embodiment are connected to the nozzle body flange 88 by wire or strap links 116 and 117 that are designed to act as hinges for beam sections 111 and 112 to ensure that forces from the plug are transmitted as a tension force on strap 114.

Also as shown in FIG. 12, the inner ends of the beam sections may be formed with upstanding projections 118 and 119 directly engaging the plug 82 so that the downward force exerted by plug 82 acts directly and more positively on the pressure floor release device. The operation is the same as in FIGS. 10 and 11 when the temperature exceeds the fusion point of solder layers 115, as this will separate strap 114 from the over ride beam and release the entire lever system regardless of the fluid pressure in the nozzle.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

l. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, means for retaining said tom of said plug means, and releasable means operable in cooperation with said lever system, said releasable means including elements connected by a heat fusible body and by a'shear pin to prevent said plug means from'being expelled from said outlet by said fluid pres-' sure when the temperature in the vicinity of said nozzle means and said fluid pressure are below predetermined values.

2. Fluid dispensing nozzle means as defined in claim 1, wherein said lever system comprises two operatively connectedlevers and said releasable means comprises wire means connected in tension between said levers.

3. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, means for retaining said plug means in said outlet comprising two levers mounted externally of said body and engaging the bottom of said plug means, said levers being operatively connected by heat fusible means releasably responsive in the presence of a first temperature, and spring clip holding means interconnecting said levers to prevent said plug means from being'expelled from said outlet by said fluid pressure when said fluid pressure is below a predetermined value, one arm of said spring clip means being a bimetallic arm adapted to spring to disable the holding action of said spring clip means in the presence of a temperature higher than said first temperature.

4. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, plug retainer means comprising a lever system mounted externally of said body and engaging the bottom of said plug means, releasable means for noramlly retaining said lever system in position to maintain said plug means in said passage blocking condition, said releasablemeans including heat fusible means operable in response to the presence of predetermined temperature to condition said lever system to permit said plug means to be expelled from said outlet by said fluid pressure, and means incorporated in said heat fusible means for holding the released plug means in said blocking condition unless said fluid pressure is above a predetermined amount.

5. Fluid dispensing nozzle means as defined in claim 4 wherein said heat fusible means comprises elements connected by a heat fusible body and said holding means comprises a shear pin connected between said elements.

6. Fluid dispensing nozzle means as defined in claim 4, wherein lever system comprises two operatively connected levers and said holding means comprises means connected in tension between said levers.

7. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, plug retainer means comprising a lever system mounted externally of said body and engaging the bottom of said plug means, releasable means for normally retaining said lever system in position to maintain said plug means in said passage blocking condition, said releasable means being operable in response to the presence of a first predetermined temperature to condition said lever system to permit said plug means to be expelled from said outlet by said fluid pressure, means for holding the plug means in said blocking condition unless said fluid pressure is above a predetermined amount, and override means responsive to a temperature higher than said first predetermined temperature to release said last mentioned holding means and allow said plug means to be expelled irrespective of the value of said fluid pressure.

8. Fluid pressure dispensing nozzle means as defined in claim 7, said releasable means comprising a heat fusible device, said holding means being a shear pin in said heat fusible device and saidshear pin being composed of. heat fusible material for providing said override means.

9. Fluid pressure dispensing nozzle means as defined in claim 7, wherein said lever system comprises two coacting levers, said holding means is a tension element connecting said levers, and said override means is a heat fusible body connecting said tension element to one of said levers.

10. Fluid pressure dispensing nozzle means as defined in claim 7, wherein said lever system comprises two coacting levers, said holding means comprises a spring clip interconnecting said levers, and said override means comprises a bimetallic arm in said spring clip. 7

l1. Fluid dispensing nozzle means comprising a body having a passage therethrough between an' inlet adapted to be connected to a source of fluid under pressure and adischarge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, plug retainer means comprising two levers mounted externally of said body and engaging the bottom of said plug means, said levers being operatively connected to said nozzle means by heat fusible means releasably responsive in the presence of a first temperature to release said levers to permit said plug means to be expelled from said outlet by said fluid pressure, and spring clip means interconnecting said levers for holding the released plug means in said blocking condition unless said fluid pressure is above a predetermined amount, one arm of said spring clip means being a bimetallic arm adapted to spring to disable the holding action of said spring clip means in the presence of a temperature higher than said first temperature.

12. A fluid nozzle comprising a body having an inlet for a source of fluid under pressure, an outlet for discharging said fluid, plug means normally blocking said outlet, means including a releasable heat fusible link for retaining said plug means in the outlet when said link issubje'cted to temperatures below a first predetermined temperature, and a shear pin in said link for retaining said plug means in said outlet when said fluid pressure is below a predetermined value, said shear pin being composed of a material that fuses at a higher temperature than said link to thereby override its holding action to release said plug means when said fluid pressure is below said predetermined value in response to said higher temperature.

13. A fluid nozzle comprising a body having an inlet for a source of fluid under pressure, an outlet for discharging said fluid, plug means normally blocking said outlet, means including lever elements and releasable temperature responsive means for retaining said plug means in the outlet when said temperature responsive means is subjected to temperatures below a first predetermined temperature, a tension member connecting said lever elements to retain said plug means in said outlet when said fluid pressure is below a predetermined value, and heat fusible means provided in the connection between said tension member and one of said elements to release said plug means when said fluid pressure is below said predetermined value in response to a temperature higher than said first temperature.

14. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to said inlet fluid pressure, plug retainer means for normally retaining said plug means in said passage blocking condition having means releasable in response to the presence of predetermined temperature to permit said plug means to be expelled from said outlet by said fluid pressure, an internal socket in said nozzle, and an upstanding post on said plug inserted intosaid socket for holding the released plug means in said blocking condition unless said fluid pressure is above a predetermined amount.

15. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, a first pair of levers mounted externally of said body and engaging the bottom of said plug means, and releasable means including a second pair of levers engaging said body and at least one of said first pair of levers to prevent said plug means from being expelled from said outlet by said fluid pressure when said fluid pressure is below a predetermined value.

16. Fluid dispensing nozzle means as defined in claim 15, wherein said releasable means further comprises strap means connected in tension between two of said levers and adapted to break when said fluid pressure is above said predetermined value to permit said plug means to be expelled from said outlet.

17. Fluid dispensing nozzle means as defined in claim 16, wherein said releasable means further comprises heat fusible means connecting said strap means to said two levers and adapted to fuse at a predetermined temperature to break the engagement between said levers and permit said plug means to beexpelled from said outlet. 

1. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, means for retaining said plug means in said outlet comprising a lever system mounted externally of said body and engaging the bottom of said plug means, and releasable means operable in cooperation with said lever system, said releasable means including elements connected by a heat fusible body and by a shear pin to prevent said plug means from being expelled from said outlet by said fluid pressure when the temperature in the vicinity of said nozzle means and said fluid pressure are below predetermined values.
 2. Fluid dispensing nozzle means as defined in claim 1, wherein said lever system comprises two operatively connected levers and said releasable means comprises wire means connected in tension between said levers.
 3. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, means for retaining said plug means in said outlet comprising two levers mounted externally of said body and engaging the bottom of said plug means, said levers being operatively connected by heat fusible means releasably responsive in the presence of a first temperature, and spring clip holding means interconnecting said levers to prevent said plug means from being expelled from said outlet by said fluid pressure when said fluid pressure is below a predetermined value, one arm of said spring clip means being a bimetallic arm adapted to spring to disable the holding action of said spring clip means in the presence of a temperature higher than said first temperature.
 4. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, plug retainer means comprising a lever system mounted externally of said body and engaging the bottom of said plug means, releasable means for noramlly retaining said lever system in position to maintain said plug means in said passage blocking condition, said releasable means including heat fusible means operable in response to the presence of predetermined temperature to condition said lever system to permit said plug means to be expelled from Said outlet by said fluid pressure, and means incorporated in said heat fusible means for holding the released plug means in said blocking condition unless said fluid pressure is above a predetermined amount.
 5. Fluid dispensing nozzle means as defined in claim 4 wherein said heat fusible means comprises elements connected by a heat fusible body and said holding means comprises a shear pin connected between said elements.
 6. Fluid dispensing nozzle means as defined in claim 4, wherein lever system comprises two operatively connected levers and said holding means comprises means connected in tension between said levers.
 7. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, plug retainer means comprising a lever system mounted externally of said body and engaging the bottom of said plug means, releasable means for normally retaining said lever system in position to maintain said plug means in said passage blocking condition, said releasable means being operable in response to the presence of a first predetermined temperature to condition said lever system to permit said plug means to be expelled from said outlet by said fluid pressure, means for holding the plug means in said blocking condition unless said fluid pressure is above a predetermined amount, and override means responsive to a temperature higher than said first predetermined temperature to release said last mentioned holding means and allow said plug means to be expelled irrespective of the value of said fluid pressure.
 8. Fluid pressure dispensing nozzle means as defined in claim 7, said releasable means comprising a heat fusible device, said holding means being a shear pin in said heat fusible device and said shear pin being composed of heat fusible material for providing said override means.
 9. Fluid pressure dispensing nozzle means as defined in claim 7, wherein said lever system comprises two coacting levers, said holding means is a tension element connecting said levers, and said override means is a heat fusible body connecting said tension element to one of said levers.
 10. Fluid pressure dispensing nozzle means as defined in claim 7, wherein said lever system comprises two coacting levers, said holding means comprises a spring clip interconnecting said levers, and said override means comprises a bimetallic arm in said spring clip.
 11. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, plug retainer means comprising two levers mounted externally of said body and engaging the bottom of said plug means, said levers being operatively connected to said nozzle means by heat fusible means releasably responsive in the presence of a first temperature to release said levers to permit said plug means to be expelled from said outlet by said fluid pressure, and spring clip means interconnecting said levers for holding the released plug means in said blocking condition unless said fluid pressure is above a predetermined amount, one arm of said spring clip means being a bimetallic arm adapted to spring to disable the holding action of said spring clip means in the presence of a temperature higher than said first temperature.
 12. A fluid nozzle comprising a body having an inlet for a source of fluid under pressure, an outlet for discharging said fluid, plug means normally blocking said outlet, means including a releasable heat fusible link for retaining said plug means in the outlet when said link is subjected to temperatures below a first predetermined temperature, and a shear pin in said link for retaining said plug means in said outlet when said fluid pressure is below a predetermined value, said shear pin being composed of a material that fuses at a higher temperature than said link to thereby override its holding action to release said plug means when said fluid pressure is below said predetermined value in response to said higher temperature.
 13. A fluid nozzle comprising a body having an inlet for a source of fluid under pressure, an outlet for discharging said fluid, plug means normally blocking said outlet, means including lever elements and releasable temperature responsive means for retaining said plug means in the outlet when said temperature responsive means is subjected to temperatures below a first predetermined temperature, a tension member connecting said lever elements to retain said plug means in said outlet when said fluid pressure is below a predetermined value, and heat fusible means provided in the connection between said tension member and one of said elements to release said plug means when said fluid pressure is below said predetermined value in response to a temperature higher than said first temperature.
 14. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to said inlet fluid pressure, plug retainer means for normally retaining said plug means in said passage blocking condition having means releasable in response to the presence of predetermined temperature to permit said plug means to be expelled from said outlet by said fluid pressure, an internal socket in said nozzle, and an upstanding post on said plug inserted into said socket for holding the released plug means in said blocking condition unless said fluid pressure is above a predetermined amount.
 15. Fluid dispensing nozzle means comprising a body having a passage therethrough between an inlet adapted to be connected to a source of fluid under pressure and a discharge outlet, plug means normally blocking said outlet and having one side exposed to fluid pressure in said passage, a first pair of levers mounted externally of said body and engaging the bottom of said plug means, and releasable means including a second pair of levers engaging said body and at least one of said first pair of levers to prevent said plug means from being expelled from said outlet by said fluid pressure when said fluid pressure is below a predetermined value.
 16. Fluid dispensing nozzle means as defined in claim 15, wherein said releasable means further comprises strap means connected in tension between two of said levers and adapted to break when said fluid pressure is above said predetermined value to permit said plug means to be expelled from said outlet.
 17. Fluid dispensing nozzle means as defined in claim 16, wherein said releasable means further comprises heat fusible means connecting said strap means to said two levers and adapted to fuse at a predetermined temperature to break the engagement between said levers and permit said plug means to be expelled from said outlet. 